Kossel Mini magnetic rod jig

thingiverse

When I assembled my first Kossel Mini, I thought there was no need to assemble its arms with good precision, so I just glued them together without a jig whatsoever. That resulted in great difficulties when I wanted to level my build platform, so now I've decided to fix this issue and do it correctly. Apparently, I didn't find any jigs for assembling magnetic rods, so I had to design my own. This jig is made for 10mm steel balls and 6mm rods. Print Settings Printer Brand: Ultimaker Printer: Ultimaker 2 Rafts: Doesn't Matter Supports: Doesn't Matter Resolution: 0.2 will be fine Infill: 50% Notes: It's recommended not to use the same Delta printer you're trying to fix because of the dimensional errors you might get from faulty rods. Try to use a printer that does all dimensions correctly, or if you don't have another printer, then use only one slot and make the new rods one-by-one. For printing, use best settings your printer can do (0.1mm layer is not necessary IMO), so you'll get nice surface finish without any blobs or misaligned layers. How I Designed This Things You'll Need To put this together, you will need: 2 printed jig pieces 4 M4 bolts and nuts with quite large washers (if you don't want to use washers, then you should print the parts with 100% infill) 4mm drill (It would be better if you have smaller drills to start with and gradually move to bigger sizes. Helps with hole placement accuracy) Printed sheet for alignment Gluestick Some kind of plate for the base of the jig Threadlocker glue EPO-based glue Assembling the Jig If you've printed out your pieces, print out the layout page and glue it to the baseplate. Then take your 4mm drill (or start with smaller sizes) and drill holes in the marked positions and put your bolts through so the nuts will be on top of the jig. Then place your printed parts to their position, tighten the nuts until they allow a slight adjustment. Put all your rods in and adjust the rig so that they have a 0.5 play in the jig, which prevents your rods from bending while gluing. Check using the lines that your jig parts are parallel to each other. Tighten all up and recheck all dimensions using a caliper or metal ruler. Preparing the Rods Separate metal bearings from threaded rods and put some threadlocker glue (I didn't have this, so I used superglue) on the thread and put it back together. E: I started to have second thoughts if gluing all the threaded rods to the ball bearings at this place is the best thing to do. It might give a little bit better results if you glue only half of the threaded rods to the ball bearings (6 pieces) and leave the other ones untouched. Other 6 pieces turn them to the maximum, then turn a few turns back so you'd have some play in them. When attaching them to the carbon rods, put the glued part to one side of the rod and the unglued part to the other. Glue them as described below. Finally, choose the best place in the jig that has no printing artifacts and fine-tune your rods (one by one!) by doing the following: Unscrew the unglued ball bearing Put some threadlock/glue to the end of the thread Screw ball bearing back Put your rod to the jig Gently start to unscrew the ball bearing until it has nearly no play in the jig Let the glue dry, and proceed with the next one I noticed that my rods don't have holes exactly in the middle. So I marked out where they are thinnest so I could align them to the jig exactly the same way. Gluing Everything! Mix a small amount of epoxy on some paper surface. I happened to have epoxy that was advised to dry in 4 minutes, and with that time, I managed to assemble two rods before the glue became unusable. Keep this in mind when dosing your glue for mixing. Apply a small amount of glue to the threaded rod and place the threaded rod into the carbon rod while slowly turning it. Use tissue to wipe off excess glue. Repeat this step with the other end and place the rod into the jig. Turn it so the previously marked mark shows up, and proceed with the next one. To be sure, leave them to dry overnight, and you're set!